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Re: [OM] Jeweler's camera

Subject: Re: [OM] Jeweler's camera
From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx>
Date: Sun, 19 Dec 2010 07:55:34 -0500
I can't argue with the results and it's clear there's something I don't 
understand if you tell me these two 80mm shots are taken at exactly the 
same distance.  In particular, at f/8 the 12MP 4/3 sensor should already 
be beyond diffraction limits on the green and red channels.  At f/8 the 
5DII is also beyond diffraction limits but only on the red channel.

Ah!  Some partial enlightenment.  Since this a macro shot, and perhaps 
at close to 1:1, the marked aperture bears not much relationship to the 
effective aperture.  So the effective aperture is smaller than f/8 and 
both cameras are beyond diffraction limits in these images.  But that 
still doesn't help me much.

Chuck Norcutt


On 12/19/2010 2:07 AM, C.H.Ling wrote:
> Here are two samples taken with Zuiko 80mm F4 at F8:
>
> 5D II, cropped both edges to make it 4:3 and scale down to 4032x3024 (same
> as E-PL1):
>
> http://www.accura.com.hk/IMG_0948c.jpg
>
> Olympus E-PL1
>
> http://www.accura.com.hk/PC193332.jpg
>
> You can see the apparent DOF on the second one looks deeper, it will be more
> so with smaller sensor.
>
> C.H.Ling
>
> ----- Original Message -----
> From: "C.H.Ling"<ch_photo@xxxxxxxxxxxxx>
> To: "Olympus Camera Discussion"<olympus@xxxxxxxxxxxxxxxxx>
> Sent: Sunday, December 19, 2010 1:21 PM
> Subject: Re: [OM] Jeweler's camera
>
>
>> You said it is the focal length not the sensor size cause different DOF,
>> so
>> consider the same sensor - FF for example. The DOF of 100mm lens at 10
>> feet
>> is 1.42ft, the DOF of 50mm lens at 5 feet (to get the same mag.) is
>> 1.44ft,
>> it is almost the same as the 100mm lens.
>>
>> C.H.Ling
>>
>> ----- Original Message -----
>> From: "Chuck Norcutt"<chucknorcutt@xxxxxxxxxxxxxxxx>
>>
>>
>>> That's not what my DOF calculator says.  If you can quantify it with a
>>> specific example I'll believe it.  But I don't think you can.  The
>>> example I used was a 100mm lens at f/8 focused at 10 feet with a CoC of
>>> 30 lines/mm.  That yields a DOF of 1.58 feet.  Then a 50mm lens at f/8
>>> also focused at 10 feet but with a CoC of 60 lines/mm.  That's to allow
>>> for a smaller image size (sensor) to be blown up twice as much as the
>>> 100mm shot such that the final print size (magnification) is the same.
>>> The 50mm lens gets a total DOF of 3.28 feet.  Slightly more than double.
>>>
>>> Chuck Norcutt
>>>
>>> On 12/18/2010 8:32 PM, C.H.Ling wrote:
>>>> I do think it is the sensor gives the increased DOF not the lens, for
>>>> the
>>>> same magnification, a 50mm lens and 100mm lens have the same DOF under
>>>> the
>>>> same aperture but the one with smaller sensor gives deeper DOF.
>>>>
>>>> C.H.Ling
>>>>
>>>> ----- Original Message -----
>>>> From: "Chuck Norcutt"<chucknorcutt@xxxxxxxxxxxxxxxx>
>>>> To: "Olympus Camera Discussion"<olympus@xxxxxxxxxxxxxxxxx>
>>>> Sent: Sunday, December 19, 2010 12:46 AM
>>>> Subject: Re: [OM] Jeweler's camera
>>>>
>>>>
>>>>> It's the short focal length that gives the increased depth of field,
>>>>> not
>>>>> the sensor.  But small sensors and short lenses do go together.
>>>>>
>>>>> Chuck Norcutt
>>>>>
>>>>>
>>>>> On 12/17/2010 11:33 PM, Andrew Fildes wrote:
>>>>>> Yes, the compact size sensor on the G12 gives a deeper DOF and I
>>>>>> forgot
>>>>>> to mention  - articulated screen. Don't do macro without one!
>>>>>> I'd imagine a tabletop set up with cube. mini-lights and table
>>>>>> tripodfd
>>>>>> for very small items, all easily repeatable on a budget. I like to put
>>>>>> a
>>>>>> small box in there and drape it with velvet offcuts for bright
>>>>>> jewellry.
>>>>>> The cube tents usually come with a drop-down front panel with hole for
>>>>>> lens. Good for anything shiny but also for any small and colourful
>>>>>> object.
>>>>>> Andrew Fildes
>>>>>> afildes@xxxxxxxxxxxxx
>>>>>>
>>>>>>
>>>>>>
>>>>
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>>
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>
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